Vaccination is an alternative method of controlling bovine tuberculosis (BTB) particularly in developing countries where the test and slaughter control method is not acceptable socially and economically. The objective of this study was to evaluate the immunogenicity of bacillus Calmette-Guerin (BCG) vaccination in bovine neonates. Twelve BTB free bovine neonates (six vaccinated with 0.5 mL of 2.4 x 10(6) CFU of BCG and six control) with age less than one month were used for this study. Interferon gamma (IFN-gamma) and antibody responses to mycobacterial antigens were determined at 0, 1, 3, 7, and 13 weeks of post-vaccination. The mean IFN-gamma response to bovine purified protein derivative, PPD in vaccinated group (Mean +/- SEM, 0.541 +/- 0.216) was greater than the mean IFN-gamma response to bovine PPD in non-vaccinated group (Mean +/- SEM, 0.253 +/- 0.101). Within the vaccinated group, the mean IFN-gamma response was greater in cross breed (Mean +/- SEM, 0.779 +/- 0.458) than in zebu breeds (0.303 +/- 0.178). No detectable antibody was observed in both vaccinated and non-vaccinated groups for 13 weeks post vaccination. A sharp rise in IFN-gamma response to bovine PPD was observed between at week 3, and then from week 3 to 7 post-vaccination, there was rapid falling of IFN-gamma response after which the response remained more or less constant in the consecutive weeks. This preliminary study showed the immunogenicity of BCG in bovine neonates under traditional cattle farming in Ethiopia.